The last Harry Potter film is once again weaving that mysterious, magical spell. But over the past few weeks things have been happening that seem more mercenary than magical.

They have led to mutterings in the publishing industry, with Potter creator JK Rowling accused of not being quite as selfless as her image sometimes suggests. Some people in the books business have been asking how much money one writer can possibly need?

It's a fair question because the numbers involved in the Potter phenomenon are certainly spellbinding: seven books selling 450 million copies; eight films grossing (so far) more than €4.5bn; in excess of €10bn in sales generated to date.

JK Rowling's share of this chamber of riches is huge: according to the March 2011 edition of Forbes magazine she has become the world's first author to earn $1bn (around €700m) from writing. So she's not short of a few Galleons (the currency in the wizarding world).

It seems, however, that you can never have enough, even when you're as rich as Rowling.

Maybe it's the memory of those hard-up days in 1994 as a single mother living on benefits in Edinburgh, when she sat in local cafés to keep warm while she wrote the first Harry Potter book with her daughter asleep in the buggy beside her -- she couldn't afford to heat her flat. And to be fair to her, she has ploughed money into charitable causes that mean a lot to her, like single-parent organisations and support groups on multiple sclerosis, the disease which killed her mother.

However, this has not stopped the criticism in the past few weeks about Rowling's moves to ensure that most of the revenue that will flow from Potter e-books will go to her and not to others.

The money stream from print books, film repeats and DVD sales will go on for years. But in the future the money from Potter e-books will be immense, with the initial rights estimated to be worth at least £100m.

Given the rapid growth in sales of e-books and readers like the Kindle, the Sony reader and the iPad, the on-going revenue will be huge. That is why the current move by Rowling is important.

Up to now, she has refused to allow her publisher to make the books available for e-readers. However, from this October the seven Harry Potter books will be available to buy as e-books -- but only through Rowling's new Pottermore.com website.

Although the author has said this will be done "in partnership" with her publisher Bloomsbury in the UK and other publishers around the world, the effect will be to drastically reduce the publishers' take from Potter e-books, a business that will be worth a fortune.

On top of that, in the past couple of weeks she has also dumped her agent Christopher Little, who is credited with discovering her 16 years ago and has represented her ever since.

Little got her the publishing deal with Bloomsbury and turned the Harry Potter novels into a multi-million pound industry. The 71-year-old agent (who Rowling picked out of a list of agents because the name sounded like a Harry Potter character) has been well paid for his efforts. He tied Rowling to his usual terms when he first signed her up: 15pc of gross earnings for the British market and 20pc for film, for the American market and for translations.

The deal, which probably has been renegotiated over the years, has made him a multi-millionaire many times over. That has not lessened his anger at losing Rowling at this stage, however, and he is said to be contemplating legal action.

It was made all the more painful because Rowling's new agent is Neil Blair, a lawyer who used to work with Little. Blair is a younger man and an expert on the legal side of e-publishing and the revenue possibilities of going online.

The effect on Bloomsbury in the UK is also likely to be significant because although the print editions of Harry Potter will continue to sell, the future is in e-books. In spite of the "partnership", the Bloomsbury share of these profits, and the share given to publishers in other countries, will be very small. The bottom line is that the Potter e-books will only be available from Pottermore.com.

Less than pleased also are the major bookstores, which opened at midnight and held special events for each new book over the years. They feel they played a big part in building up the Potter phenomenon. Now they are being made to vanish from the Potter e-book business with a wave of the Rowling magic wand.

The manner in which all this has come about has caused a lot of cynical comments in publishing circles in the past two weeks.

The Pottermore.com website was initially presented as payback by Rowling to her loyal fans, a gift which would bring them all sorts of free online Potter experiences.

"I wanted to give something back to the fans that have followed Harry so devotedly over the years," said Rowling in a promotional video.

It might have sounded like a giveaway but it's nothing of the kind, those in the books trade say. The project to put Potter online had been shrouded in mystery from the start, with rumours about a forthcoming site flooding the internet. The hype started months ago when Rowling set fans a series of clues, asking them to enter 10 sets of co-ordinates into secretstreetview.com. A letter could be found at each location and when arranged in the right order they spelled out the name Pottermore.

When fans googled this, they found Pottermore.com, which had the words 'Coming Soon' and Rowling's signature. The speculation was that the new site would be an interactive meeting place for fans and might even have news about an eighth Harry Potter book.

A month ago, with interest having reached fever pitch, Rowling released the promotional video explaining that the new website would build a complete interactive online Potter world for fans.

She said she had written 18,000 additional words giving more background to the characters, places and objects for the site and that she had also helped develop interactive web experiences and gaming elements.

Pottermore would let the user choose a magic username and join Hogwarts in the virtual world just as Harry does in the books, Rowling's team explained. Interactive features would include a digital 'Sorting Hat', which allocates Hogwarts' students to a house, and a 'Wand Chooser', a tool that selects the appropriate wand for a user based on a series of questions.

It also became clear that new agent Blair and Sony were heavily involved in the venture and that Sony had registered the Pottermore name last year.

With all the exciting talk about online gaming and a Potter interactive world, one important point was somewhat overlooked: the Pottermore.com website will be the ONLY place Harry Potter e-books can be bought.

The rest is not just window-dressing because Pottermore will clearly be at the cutting edge of online interactive experience. But underlying this will be the fact that the site will enable the revenue from e-book sales to be controlled by Rowling and not by her publishers. And with Sony she will also control revenue from online activity on the site.

An additional benefit for Rowling will be that her team will have demographic and contact details for the millions of Potter fans who register on the new site, which will give her a unique platform to promote Potter products, games and content of all kinds, perhaps with other partners.

The merchandising of Potter has been relatively restrained up to now, because that's the way Rowling wanted it. Even so, there are around 400 authorised products out there already. There is also the Wizarding World of Harry Potter attraction in Orlando and a British Potter theme park is due to open next year.

Pottermore is part of this, the transformation of Harry Potter into an enduring global brand that will be developed hugely in the years ahead to become as everlasting as Peter Pan.

Today's Potter generation will want to introduce Harry to their children a decade or two from now and they will be encouraged to do so.

An executive at Brand Licensing Europe in the UK values the Potter brand at £9bn, and believes the selling power of the name can continue to grow, even without new books or movies, through merchandise, amusement parks and video games.

It all seems to be more about money than magic. But then we do live in the Muggle world.